In certain applications it is necessary to precisely locate a plurality of optical fibers relative to each other. For example, the information carrying capacity of a single optical fiber can be greatly increased by the use of multiplexing and demultiplexing techniques. One of these techniques utilizes wavelength division multiplexing and demultiplexing devices that depend on diffraction gratings to separate or combine light by wavelength. In a demultiplexing application, the diffraction grating separates light on the link fiber by wavelength and focuses each wavelength to a separate precisely located position where the receiver fibers are located. In a multiplexing application, the light on the transmitter fibers is combined and focused onto the link fiber. Thus, the fibers should be reliably, repeatably and accurately positioned to minimize insertion losses.
The basic approach to accurately and reproducibly positioning fiber has been to form a fiber array and to design the multiplexer and demultiplexer around the array. Known fiber arrays, however, have not satisfactorily provided the desired objects. Metcalf and Providakes (Applied Optics, Vol. 21, No. 5, Mar. 1, 1982) provide a device wherein the input and output fibers are aligned in a side-by-side array cemented between two microscope slides and polished. Interpretation of the data in their paper, however, shows that the spacing between the output peaks shown in FIG. 3 are not constant. This means that there were small, variable spaces between the fibers in the array which caused misalignment with the received light resulting in excess insertion losses.